Pretreatment of porous metal oxide catalysts for use in dehydrogenation and other reactions

Abstract

Methods of activating and/or reactivating a catalyst composition comprising a porous metal oxide (MOx) catalyst are disclosed. Methods of catalyzing a reaction using a catalyst composition comprising a porous metal oxide catalyst activated and/or reactivated by such a method are also disclosed.

1 . A method of activating and/or reactivating, via a surface cleaning reagent, a catalyst composition comprising a porous metal oxide (MO x ) catalyst, wherein:
 the surface cleaning reagent possesses at least one of the following characteristics:
 possesses reactivity with one or more bound species derived from CO 2  and/or H 2 O via a stoichiometric reaction; 
 does not lead to one or more reactions that form a surface titrant of a Lewis acid-base pair; and/or 
 can desorb from a surface of the porous metal oxide catalyst without leaving behind surface debris that can irreversibly titrate an M-O active site of the porous metal oxide catalyst; and further wherein: 
   if the porous metal oxide catalyst is ZrO 2 , then the surface cleaning reagent is not dimethyl ether or propylene.   
     
     
         2 . A method of activating and/or reactivating, via a surface cleaning reagent, a catalyst composition comprising a porous metal oxide (MO x ) catalyst, wherein:
 the surface cleaning reagent is chosen from alcohols, ketones, carboxylates, acids, esters, ethers, hemiacetals, hemiketals, acetals, ketals, orthoesters, orthocarbonates, organic acid anhydrides, and combinations thereof; and further wherein:   if the porous metal oxide catalyst is ZrO 2 , then the surface cleaning reagent is not dimethyl ether or propylene.   
     
     
         3 . A method of activating and/or reactivating, via a surface cleaning reagent, a catalyst composition comprising a porous metal oxide (MO x ) catalyst, wherein:
 the surface cleaning reagent comprises at least one compound chosen from ROH, RCOR′, RCHO, ROCOOR′, RCOOH, RCOOR′, R 2 CH(OR 1 )(OH), RC(OR″)(OH)R′, RCH(OR′)(OR″), RC(OR″)(OR′″)R′, RC(OR′)(OR″)(OR′″), C(OR)(OR′)(OR″)(OR′), and R 1 (CO)O(CO)R 2 , wherein each of R, R′, R″, R′″, R 1 , and R 2  is independently chosen from alkyl, alkenyl, alkynyl, and aryl groups; and further wherein:   if the porous metal oxide catalyst is ZrO 2 , then the surface cleaning reagent is not dimethyl ether or propylene.   
     
     
         4 . The method according to  claim 1 , wherein the porous metal oxide catalyst possesses a surface with an M-O site of the Lewis type and of balanced acid-base strength. 
     
     
         5 . The method according to  claim 1 , wherein a surface of the porous metal oxide catalyst stabilizes anionic and/or cationic moieties that form at transition states for heterolytic processes that form and cleave C—H bonds. 
     
     
         6 . The method according to  claim 1 , wherein a metal (M) of the porous metal oxide catalyst does not undergo reduction to a lower oxidation state in a reductive environment typical of hydrogenation-dehydrogenation catalysis. 
     
     
         7 . The method according to  claim 1 , wherein the porous metal oxide catalyst comprises at least one of ZrO 2 , Y 2 O 3 , CeO 2 , and CoO. 
     
     
         8 . The method according to  claim 1 , wherein the porous metal oxide catalyst is chosen from oxides of Y, Ce, and Ti, and mixed oxides thereof. 
     
     
         9 . The method according to  claim 1 , wherein the porous metal oxide catalyst comprises one or more of Y, Nb, B, Ga, Co, and Mo on ZrO 2 . 
     
     
         10 . The method according to  claim 1 , wherein:
 the porous metal oxide catalyst comprises one or more of Mg, Ca, Sr, Ba and La on a zirconia support; or   the porous metal oxide catalyst comprises ZrO 2 -silica, zirconia-alumina, zirconia-titania, or a combination thereof.   
     
     
         11 . The method according to  claim 1 , wherein the porous metal oxide catalyst comprises ZrO 2 , Y-stabilized ZrO 2 , or Y 2 O 3 . 
     
     
         12 . The method according to  claim 1 , wherein the surface cleaning reagent is chosen from dimethyl ether, propylene, methanol, tert-butyl alcohol, methyl tert-butyl ether, di-tert-butyl ether, anisole, dimethyl carbonate, and combinations thereof. 
     
     
         13 - 15 . (canceled) 
     
     
         16 . The method according to  claim 1 , wherein the pretreating is performed at a temperature of up to 900 K. 
     
     
         17 - 23 . (canceled) 
     
     
         24 . The method according to  claim 1 , further comprising pretreating the catalyst composition in an aerobic oxidative environment before or after the pretreatment with the surface cleaning reagent. 
     
     
         25 . A method of catalyzing a reaction on a catalyst composition comprising a porous metal oxide catalyst, the method comprising activating and/or reactivating the catalyst composition using the method of  claim 1 , wherein the reaction is chosen from alkane dehydrogenation, alkene hydrogenation, olefin-paraffin alkylation, methanol synthesis from CO/H 2  mixtures without O-rejection as H 2 O or CO 2 , C—C bond formation via alkene oligomerization or metathesis, dehydrocyclization (alkanes/alkenes to arenes), dehydrocyclodimerization (alkanes/alkenes to arenes with a larger number of C-atoms), transfer hydrogenation, hydroformylation/carbonylation, aromatization, dearomatization, reforming, isomerization, and bifunctional reactions in which one of the aforementioned functions can be combined with a Brønsted acid function. 
     
     
         26 . The method according to  claim 25 , wherein the bifunctional reaction is chosen from catalytic reforming for octane enhancement, alkane hydroisomerization, hydrocracking, isodewaxing, fluid catalytic cracking, and reactions converting C 3 -C 4  alkanes to aromatics. 
     
     
         27 . The method according to  claim 25 , wherein the reaction is propane dehydrogenation. 
     
     
         28 . The method according to  claim 25 , wherein the porous metal oxide catalyst comprises at least one of ZrO 2 , Y 2 O 3 , CeO 2 , and CoO. 
     
     
         29 . (canceled) 
     
     
         30 . The method according to  claim 25 , wherein the porous metal oxide catalyst comprises ZrO 2 . 
     
     
         31 . The method according to  claim 25 , wherein the porous metal oxide catalyst comprises Y-stabilized ZrO 2 . 
     
     
         32 - 38 . (canceled)